Antistatic treatment of hydrophobic fiber



Patented Apr. 20, 1954 UNITED STAT E TNT OFFICE ANTISTATIC TREATMENT OFHYDR-OPHOBIC F IBER ware No Drawing. Application January 9, 1951, SerialNo. 205,235

Claims.

This invention relates to non-cellulosic, hydrophobic textile materialshaving improved physical characteristics. More particularly, thisinvention deals with fibers, filaments, fabrics or other forms ofsynthetic, non-cellulosic textile materials such as nylon,polyacrylonitrile, polyethylene terephthalate and their variousmodifications.

Fibers of the aforementioned type are well known for their poorelectrical conductivity. As a result, they tend to accumulateelectrostatic charges in working, as for instance in the textile mill,or in service, as for instance in a rug. Such charges may be annoyingfor instance by causing a nylon dress to cling to the body of thewearer, interfering with the intended graceful hang of the garment; butthey are worse than annoying in the textile mill, where such staticcharges, formed through repeated friction of the fiber, filament oryarn, may prevent proper spinning, drawing, twisting, weaving orknitting.

It is accordingly an object of this invention to provide textilematerials of the aforementioned classes, which through treatment with anagent as defined below, shall be essentially free of noxiouselectrostatic qualities, or shall in any event be comparable in theirworking qualities to cotton, in so far as static charges are concerned.

Although the general idea of treating textile fiber with anti-staticagents is old, the problem of selecting a proper agent is by no means asimple one. In the first place, the nature of the fiber to be treatedmust be taken into account. Thus, agents which have been indicated inthe art as suitable for W001, viscose or cellulose acetate, do not as arule produce good anti-static effects on hydrophobic, non-cellulosicfiber. Secondly, when an effective agent has been found it must answerstill other qualifications; for instance, it must be compatible withlubricants, sizes and other agents commonly applied to fiber in themill. It must allow proper running tensions of filament during drawingand twisting operations. It must be non-corrosive of the apparatus uponwhich the fiber will be worked, and it must be non-toxic and have noinjurious dermatological effects upon the worker or upon the ultimatewearer.

Now, according to this invention excellentanti-static efiects uponnon-cellulosic, hydrophobic textile materials are obtained by, using aspecial group of agents which may be defined broadly as mixtures ofamine salts of long-chain alkyl phosphates, whereof the amine portion isan oxy-alkylene amine, such as mono-, di-, and

triethanol amine, the ethanol derivatives of monomethyl and dimethylamine, and morpholine. In other words, the group of agents found usefulaccording to this invention are mixtures, composed of compounds definedby the general formula-- wherein m designates the numeral 1 or 2, whiley is the difference between 3 and at, Alk is a normal, alkyl radicalhaving from 8 to 16 carbon atoms, and NX represents an oxyalkylene amineselected from the group consisting of the three ethanolamines, the threeethanol-methylamines (i. e. monoethanol-mono-methylamine,ethanoldimethylamine and diethanol-methylamine) and morpholine.

I find that I obtain .best results with mixtures of amine-salts ofvarious alkyl-phosphates. Thus, a mixture of mole percent ofgives verymuch superior results to an agent consisting of the purediamino-monoester. The superiority of the agent increases as theproportion of diester in the mixture increases, and for a 50:50 mixtureit reaches a maximum appreciably superior to that obtainable from eitherof its pure components. The anti-static effects are nevertheless stillveryhigh when the agent consists of pure monoamino-diester. Altogetherthen, it may be summarized as a general rule that the agent according tothis invention should comprise a reaction product of phosphoruspentoxide, a straight-chained saturated primary, monohydric alcohol ofmore than 6 carbon atoms and an oxyalkylene amine as above defined, withthe proviso that the reaction product shall comprise at leastsubstantial quantities of the monoamino diester component.

In addition, they have the quality of being readily soluble in alcoholand self-dispersible in water, so that they may be applied to the fiberfrom either medium.

Their electrostatic effect is very high and rates from good to excellentin standard tests recently developed for measuring anti-static effects.

A particularly good effect is obtained when NX in the above generalformula is a diethanolamine, and the best results in this group areobtained when the agent is an essentially equimolecular mixture of twoesters of the formula OAlk O=PO Alk ONH2(C2H4OH):| and /OAlkO=P-ONH2(C2H4OH) ONH2(C2H4OH)2 which is obtained for instance byreacting one mole of phosphorus pentoxide with about 3 moles of theselected alcohol and then reacting this intermediate product with 3moles or more of diethanolamine.

The quantity of agent required per unit weight of fiber is not high. Aloading of agent as low at 0.02 gm. per 100 gm. of fiber will produce aremarkable improvement in electrical conductivity. Loadings as high as 2by weight of the fiber may be used. More. commonly, however, loadings of0.04 to 0.4% will be found both satisfactory and. economical.

Without limiting my invention the. following 2 examples are given toillustrate my preferred mode of operation. Parts mentioned are byweight.

PART A.-PR.EPA-.RATION OF THE AGENTS Ezramplei To a stirred mixture of 1mole of n-cctanol-l, 1 mole of n-decanol-l, and 1 molecular equiva lentof Lorol (a commercial mixture. of primary alcohols, predominantly C12and Col) was added over a period of .5 hours 1 mole of phosphoruspentoxide, keeping the reaction temperature below C. The mixture wasthen stirred at '-55 C. for 1.5 hours and then further stirred at tiff-C. until complete solution was effected. Three moles of diethanolaminewere then added to the hot reaction mixture at such a rate as not topermit the reaction temperature to exceed C'., and stirring was 4continued until the exothermic reaction subsided. The product was ayellow, oily liquid.

Example 2 Three moles of n-octanol-l' were substituted for the alcoholmixture used in Example 1.. Theproduct was a clear liquid.

Example I? A, mixture, of 1.5 moles of nrhexancl l and 1.5. moles ofcetyl alcohol was. substituted for the alcohol mixture used inExample 1. The prodnot was a. soft grease.

Example 4 The procedure was as in Example. 1, but three moles of Ocenol(octadecenol-l) were used, yielding a dark brown thick oil.

Example 5 The procedurev was as in Example. 1, but: instead of:diethanolamine. 3 moles of triethanolamine were used. The product was ared-brown heavy oil.

Lil

4 Example 7 The procedure was as in Example 1, except using 3 moles ofmorpholine. This gave a clear, medium-viscosity, red brown oil.

Example 8 The procedure was as in Example 1, except using 3 moles ofdimethylethanolamine. A reddish oil was obtained.

Example 9 The procedure was as in Example 1, except using 3 moles ofmethyldiethanolamine. The product was; a yellow oil.

Example 10 V The procedure was as in Example 2, except using 2.75 molesof octanol-l to 1 mole of P205. The product was a yellow brown grease.

Example 11 The procedure was as in Example 2, except using 3.75 moles ofoctanol-l to 1 mole. of P205. The product was yellow orange oil.

Eaample 1.2 In a manner similar to Examples 10 and 11, by varying theproportion of alcohol to P205 in the first part of the process, thefollowingthree compositions of matter were prepared and isolated:

(a) bis-diethanolamine.

phosphate; 7

(b) the diethanolamine salt of dilauryl phos- (.c) and equimolecularmixture of (a) and (b).

These were used for the tests described in Example l9 hereinbelow.

PART B.-APPLICATION The evaluation of electrostatic properties in theexamples hereinbelowwas carried out. essentially as follows: V

A small piece of hydrophobic fabric (approximately l x' 5") is. weighed;under conditions of controlled humidityand immersed for so see. inapproximately 336-5 cc. of a 9.5. ethanol. solution of theanti-staticagent. conta ning- 1 g; oi the; agent. The fabric is removed,air-dried, and weighed again to provide a basis for calculatingthepick-up of antiestatic agent. For comparative tests, a loading of 0.05%agent on nylon taffeta. was adopted as. standard.

A strip. 3: cm... wide is. then. cut off, and its electrical resistance.at a controlled. relative. humidity saltof monolauryl of; 25 is.measured on a special apparatus which separated by a comprises: two;electrodes; space of; 1.25 cmand having a potential difference of volts.The fabric. is held in place between the electrodes so as to provide acon ducting area 1.25 cm. long. and 3 cm. The reading' gives theresistance of this standard area in ohms. For practical purposes theresults are rated. as. follows:

(The rating or the untreated control in the non-cellulosic, hydrophobicfibers herein discu sed is usually 1111-) Example 1 3 Each agent whosepreparation is described in Examples 1 to 11 was applied separately tonylon, polyacrylonitrile and polyethylene terephthalate woven fabrics.This was done by padding for approximately 30 seconds in 250 parts byweight of 95% ethanol containing 1 part by weight of the anti-staticagent. After wringing the fabrics to wet pick-ups of 0.1-0.3 (ratio ofliquid to dry fabric by weight), the fabrics were air-dried. Activeingredient loadings of 0.04-0.12% (based on dry weight or" fabric) werethen obtained. Electrical resistance of the treated fabrics, as measuredby the above-described standard method, were as follows:

Anti-static Product Rating Excellent. Very good.

Example 14 Example 15 Nylon, polyacrylonitrile and polyethyleneterephthalate fabrics were treated by the method of Example 13, usingthe product of Example 1 in ethanol solutions of sufiiciently increasedccncentrations to produce loadings of 2.0% by weight. Th treated fabricshad anti-static ratings of excellent. The coatings were of a lubricativenature, but they were not objectionably oily.

Example 16 200 parts of the product of Example 1 were dispersed in 250parts or water containing 3.5 parts of a sodium alliylsulfate preparedfrom higher alcohols averaging C10. The resulting emulsion was mixedvery vigorously and 200 parts of a high boiling white mineral oil(boilin range, coo-350 C.) were stirred in. The resulting paste had anactive ingredient content of 61 A spinning finish bath was prepared bydispersing 100 of this paste in 500 g. of water. plied to nylon filamentimmediately after extrusion of the melt, by passing the filamenttangentially over a glass wheel revolving in the bath. In this mannerloadin s of the anti-static agent amounting to from 0.05 to 0.4% byweight of the filament were obtained. The anti-static rating of thetreated fibers was excellent.

In this same manner nylon fiber has been trea with numerous otheranti-static agents falling within the above general formula. In everySince the water pick-up of It was apcase an excellent anti-static effectwas imparted to the fiber.

Example 17 To parts of an emulsion of medium viscosity mineral oil (40sec. white oil) in water containing 11.2% oil, 3 parts of the alkylphosphate described in Example 1 were added. This mixture was runthrough a Disper-mil, and a homogeneous emulsion was obtained. Itcontained 11.2% oil solids, 3% anti-static agent and 85.8% water.

In substantially the same manner as described in Example 13, a loadingof 0.5% total finish was applied to nylon fiber, giving approximately0.11% of the anti-static agent on the fiber. The fiber had ananti-static rating of excellent.

When the same procedure was applied to polyacrylonitrile fiber and topolyethylene terephthalate fiber, similar, high anti-static effects wereobtained.

Example 18.Com;oatibility with. com'ng oils Five parts of thecomposition described in Example 1 were dissolved in 100 parts of butylpalmitate (a conventional coning oil) usin approximately 5 parts ofocenol as solubilizin agent. The resulting solution was applied to nylonfiber by passing the fiber over a roll in contact with the oil. Thetreated fiber was found to have an anti-static rating of good toexcellent.

Example 19. uperiority of mixed agents (a) The bis-diethanolamine saltof monolauryl phosphate was applied to nylon from an alcoholic bath, inthe manner described in Example 13, to produce various loadings rangingfrom 0.04 to 0.12% by weight. In all cases, the anti-static qualities ofthe fabric were found to rate poor to fair, on the above standard table.(b) When the diet-hanolamine salt of dilauryl phosphate was tested inthe same manner and in the same range of loadings, the treated fabrictested good.

(0) In the same manner an agent made from three moles of diethanolamineand a 1:1 molar mixture of monoand dilauryl phosphate was tested andfound to have an anti-static rating of very good.

It will be understood that the details of the above examples andprocedures may be varied widely, within the skill of those en aged inthis art. 7

Thus, in the synthesis of the agent, the reaction between phosphoruspentoxide and the selected alcohol (or mixture of alcohols) and thesubsequent reaction between the intermediate esters thus obtained withthe selected oxy-alkylene amine, are both exothermic and requirecooling; but the ultimate temperature maintained during each step of thereaction may be anywhere between 20" and 100 C.

The products can be applied to hydrophobic fibers in several ways.Filaments may be treated immediately after extrusion of the hydrophobicmelt or solution. A tow of many threads of spun filament may be treatedat some stage prior to the crimper, as in the manufacture of staplefiber. The agents may also be applied in the coning or winding oil, in asizing bath or in a padding bath for fabric or skeins.

For the purpose of comparison, many agents of a chemical structurefalling outside the limits of the generic formula hereinabove have beentested by me by the same standardprocess as hereinabove. The followingtables show the antistatic ratings thus obtained. All tables refer toesters obtained as above by reacting a mixed alkyl phosphate (1 moleP2053 moles of the respective alcohol) with an oxy-alkylene amine asnamed in each case.

binol). di-isopropyl methyl (from di-isopi'opyl carbiu0l) mixed hfiptyland higher alkyl (secondary, branched).

D0. oxy-bisethylene (from diethylene glycol) fair. mixed 11-0 and higheralkyl oxy-bisethylene Do. the radical of blown castor oil poor. theradical of raw castor oil Do.

TABLE IL-USING THROUGHOUT THE MIXED ALKYL ESTER DEFINED IN EXAMPLE IAmine or base g igg dietlianolamine. excellent. monocthanolamine verygood. triethauolarnine" Do. morpholine Do. dimethylethanolamine Do.methyldiethanolamine excellent. diethylenetriamine nil.beta-aminoethyl-ethanolam e poor glycine Do.

nil. pyridine Do. sodium hydroxide Do.

It is clear from the above tables that only when the alkyl radical islonger than Cs and only when the amine is an oxy-alkylene amine as abovedefined does the mixture of alkyl amine phosphates give anti-staticratings better than fair.

In addition, the preferred agents of this inven-- tion were tested forother qualities essential for their use in treating textiles, such asease of dispersion, stability of the aqueous emulsion, rate of pick-upby the fiber, stability to heat and to storage, and compatibility withthe other agents with which they were applied. In all cases my preferredagents as defined by the above general formula were found to rate goodto very good.

All these qualities make my novel agents additionally valuable for usein spinning finishes, staple finishes, coning and winding oils and insizing baths. Furthermore, they can be sprayed onto waste fibers whichaccumulate in textile processing mills, so that these scraps can berecovered by passing them through the picking and carding operationswithout interference by electrostatic charges.

As for the chemical nature of the fiber to be treated, this invention isapplicable in general to non-cellulosic, hydrophobic textile fibers.Hereinabove we have discussed nylon, polyethylene terephthalate..polyacrylonitrile and their various modifications. As instances of theV latter may be mentioned polymers of acrylonitrile :8 which have beenmodified by copolymerization with substantial amounts of other vinylcompounds such as vinyl pyridine, vinyl chloride, styrene or vinylacetate; polyacrylonitrile which is mixed with other materials such asplasticizers, modifiers, etc.; linear polyesters of ethylene glycol andterephthalic acid which have been modified by the addition of up to 10of other glycols and/or dibasic acids; and polyethylene terephthalatewhich is mixed with other materials such as plasticizers, modifiers,etc. These fibers are all well known in the literature, and many of themare common commercial products. See for instance, Carothers, U. S. P.2,071,250; 2,071,253 and 2,130,948; Whinfield et al., U. S. P.2,465,319; Jacobson, U. S. P. 2,436,926; Latham, U. S. P. 2,404,714 andArnold, U. S. P. 2,491,471.

It will be understood that although this specification is concernedprimarily with textile fibers, my novel agents may be applied also tothe above indicated chemical materials in non-textile form, for instancesheets or shaped masses.

These agents are effective on any hydrophobic substrate which tends toaccumulate an electrical charge. Such substrates may also includepolyethylene, polystyrene, polyvinyl chloride, polyvinylidene chloride,copolymers of these chlorides with acrylonitrile,polytetrafluoroethylene, polychlorotrifiuoroethylene, copolymers of thelatter two, polyvinyl fluoride. etc., in either fiber or massive form.

I claim:

1. A process of improving the electrostatic qualities of non-cellulosic,hydrophobic textile fiber which comprises impregnating the same with amixture of agents of the general formula wherein Alk represents astraight-chained, saturated primary aliphatic hydrocarbon radical of 8to 16 C-atoms, NX represents an oxyalkylene amine selected from thegroup consisting of the ethanolamines, the N-methyl-ethanolamines andmorpholine; :c is an integer not greater than 2, while y is thedifierence between 3 and 2. A process of improving the electrostaticqualities of non-cellulosic, hydrophobic textile fiber which comprisesimpregnating the same with an agent comprising a diethanolamine salt ofmixed monoand di-allzyl phosphates, the alkyl radical whereof is astraight-chained, saturated, aliphatic, primary, hydrocarbon radical of8 to 16 C-atoms.

3. Non-cellulosic, hydrophobic textile fiber having incorporated thereinfrom 0.02 to 2.0% by weight of an antistatic agent of the generalformula wherein All: represents a straight-chained, saturated,aliphatic, primary, hydrocarbon radical of whereof is astraight-chained, saturated, alialiphatic, primary hydrocarbon radicalof from phatic, primary hydrocarbon radical of 8 to 16 8 to 16 C-atoms.

C-atoms.

5. Non-cellulosic, hydrophobic textile fiber fieffilences Cited in thefile Of this Patent having incorporated therein from 0.02 to 2.0% by 5NITED STATES PATENTS weight of a composition of matter being asubstantially equimolecular mixture of monoalkyl- Number Name Date2,005,619 Graves June 18, 1935 b1s(d1ethanolam1ne)-phosphate anddialkyl- 2,127,495 Tulleners Aug. 23, 1938mono(d1ethanolam1ne)-phosphate, wherein the 2 413 428 Billings Dec 311946 alkyl radical is a. straight-chained, saturated, 10

3. NON-CELLULOSIC, HYDROPHOBIC TEXTILE FIBER HAVING INCORPORATED THEREIN FROM 0.02 TO 2.0% BY WEIGHT OF AN ANTISTATIC AGENT OF THE GENERAL FORMULA 